This invention relates to a method of building a strengthened, embanked foundation of roadbed and the like.
When such a new road as a high way is constructed to intersect already existing roads, water-ways or the like, there has been generally employed a method of building an embankment at least over the existing road or the like to have the new road constructed on the embankment in a two level crossing. In this case, it is necessary to build a hollow structure transversely through the embankment so as to secure a space necessary for retaining the existing road or the like. Specifically, such hollow structure includes a concrete-made tunnel, substructures for a bridge, box structure or the like, and the peripheral portions of this structure must be sufficiently stabilized for preventing its side walls and ceiling from being broken or collapsed.